The present invention relates to methods and compositions of treating subterranean formations with a novel resin system.
Subterranean wells are often stimulated by hydraulic fracturing treatments. In hydraulic fracturing treatments, a viscous treatment fluid is pumped into a portion of a subterranean formation at a rate and pressure such that the subterranean formation breaks down and one or more fractures are formed. While the treatment fluid used to initiate the fracture is generally solids-free, typically, particulate solids, such as graded sand, are introduced in a later portion of the treatment fluid and then deposited into the fracture. These particulate solids, (generally known as “proppant particulates” or, simply, “proppant”) serve to prop the fracture open (e.g., keep the fracture from fully closing) after the hydraulic pressure is removed. By keeping the fracture from fully closing, the proppants aid in forming conductive paths through which produced fluids, such as hydrocarbons, may flow.
Hydraulic fracturing of subterranean wells is often performed in formations that contain unconsolidated particulates. The unconsolidated particulates may migrate out of the subterranean formation and be produced with production fluids. The presence of unconsolidated particulates in a formation during production is undesirable because they may damage or abrade producing equipment or reduce well production. For example, unconsolidated particulates may migrate into wellbore casings, perforations, or the interstitial spaces between packed proppants within a fracture and clog or hinder well production. As used herein, the term “unconsolidated particulates” refers to any loose or loosely bonded particulates that may move through the formation with production fluids. Unconsolidated particulates may include, for example, sand, gravel, proppant particulates, and/or formation fines.
One method of controlling unconsolidated particulates in hydraulic fractured subterranean formations is to perform a gravel-packing treatment. In gravel-packing treatments, particulates are deposited into unconsolidated or weakly consolidated formation zones to create a physical barrier to the transport of unconsolidated particulates with the produced fluids. Typical gravel-packing treatments include placing a screen in a wellbore and packing the annulus between the screen and the wellbore with particulates of a certain size to prevent the transport of unconsolidated particulates with the produced fluids without compromising the conductivity of the well. Gravel-packing treatments, however, involve placement of additional unconsolidated particulates into the wellbore which may not be adequately maintained, for example, by a screen and which may, therefore, migrate along with the produced fluids, thus, contributing to the problem the gravel-packing treatment was attempting to solve.
Another method of controlling unconsolidated particulates is to treat the wellbore with a consolidating agent. In such treatments, a consolidating agent is placed into the wellbore in order to stabilize unconsolidated particulates, such as by providing a tacky substrate for unconsolidated particulates to adhere or by contacting unconsolidated particulates and curing into a hardened mass. As used herein, the term “tacky,” in all its forms, refers to a substance that is at least somewhat sticky to the touch. Typically, the consolidating agent may be used to lock unconsolidated particulates in place and form at least a partially immobilized substance, which may be accomplished by enhancing grain-to-grain or grain-to-formation contact of the unconsolidated particulates.
The present invention provides a novel system for treating unconsolidated particulates that is capable of hardening to lock the particulates into place and that may additionally possess non-hardening qualities such that it provides a partial tacky substrate for further control of the particulates.